code: def from_str(cls, stage: str):
      if stage == "train":
          return TRAIN
      elif stage == "predict":
          return PREDICT
      elif stage == "cross_validation":
          return CROSS_VALIDATION
      elif stage == "default":
          return DEFAULT
      else:
          raise ValueError(f"stage {stage} is not supported")
  
file_path: FATE/python/fate/components/core/essential/_stage.py
label_desc: Use image node_id 7 for calling the Stage obj's underlying member method code with example usage: obj.from_str(cls, stage) and returns: TRAIN, PREDICT, CROSS_VALIDATION, DEFAULT